Globals have been long considered undesirable due to the complexity and risk they create.
E.g. you may want to create a function called onStart() to run at the start of a workflow, except that's taken by the software's event handler and would collide and create unexpected behavior.
That said, just loadLibrary() your file and it'll install whatever's in the global namespace there to the entire workflow. This is best done at the workflow level, i.e. Properties dialog, to make it centralized and predictable.